Calcium in Pregnancy Only Good for Preventing Hypertension

Yael Waknine

October 11, 2011

October 11, 2011 — Calcium supplementation in pregnancy does not prevent preterm birth or low infant birth weight and may only help to reduce the risk for pregnancy-related hypertension, according to a study published in the latest issue of the Cochrane Database of Systematic Reviews.

For the study, researcher Pranom Buppasiri, MD, from the Department of Obstetrics and Gynecology at Khon Kaen University in Thailand, and colleagues obtained data from 21 studies (n = 16,602) in the Cochrane Pregnancy and Childbirth Groups trials register.

A systematic review found that calcium supplementation during pregnancy had no protective benefit in decreasing the risk for preterm birth, defined as less than 37 weeks' gestation (risk ratio [RR], 0.90; 95% confidence interval [CI], 0.73 - 1.11; 12 studies, n = 15,615 women), and also less than 34 weeks' gestation (RR, 1.11; 95% CI, 0.84 - 1.46; 3 trials, n = 5145 women).

Calcium supplementation was likewise not associated with a decreased risk for low birth weight (RR, 0.91; 95% CI, 0.72 - 1.16; 4 trials, n = 13,449 infants), but instead was linked to a slight increase in birth weight (mean difference, 64.66 g; 95% CI, 15.75 - 113.58 g; 19 trials, n = 8287 women). No beneficial effect on maternal bone density was observed.

However, previous research published by Hofmeyr et al in August 2010, using Cochrane trial data, suggests that use of calcium supplements during pregnancy might help prevent preeclampsia by preventing maternal hypertension (RR, 0.65; 95% CI, 0.53 - 0.81; 12 trials, n = 15,470), thereby decreasing the risk for preeclampsia (RR, 0.45; 95% CI, 0.31 - 0.65; 13 trials, n = 15,730) and reducing the composite risk for maternal death or serious morbidity (RR, 0.80; 95% CI, 0.65 - 0.97; 4 trials, n = 9732).

"This may be evidence that routine calcium supplementation in pregnant women for preventing preterm birth and low birth weight is not warranted," the authors of the new study note, adding that its use may be indicated in women at risk for hypertension.

The study was supported by the NHS National Institute for Health Research. Additional support was provided by the SEA-ORCHID Project and the Thai Senior Researcher Fund.

Cochrane Database Syst Rev. 2011;10. Abstract


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